1. Field of the Invention
The present invention relates to a sheet feeder for an image formation apparatus and, more specifically, to a sheet feeder that has rotatable guides for selecting an automatic or a manual sheet feeding mode.
2. Background Art
An image formation apparatus (e.g., a printer, scanner, facsimile or copier) must often accommodate printable mediums having a thickness or dimensions different from that of standard paper. Envelopes, postcards, transparencies, labels and resume paper are just a few examples of the different printable mediums that a sheet feeder must accommodate. A sheet feeder may be constructed to use a tray that supplies paper to a printer. The tray often has an adjustment lever allowing the paper to be moved away from a pickup roller in order to load additional sheets of paper into the tray. After loading additional paper, the adjustment lever is moved in a direction opposite that used for preparing the tray to receive additional paper causing the pickup roller to press against the paper on the tray and then transfer the paper to a transfer roller. Then, the transfer roller transports the sheet of paper to the printer cartridge.
Other sheet feeding devices have also been developed, such as, U.S. Pat. No. 5,419,543 to Nakamura entitled Paper Feeding Apparatus for Printer, that shows a paper tray pushed by a bell crank towards a pickup roller at regular intervals to load paper. U.S. Pat. No. 4,585,218 to Williams entitled Mechanism for Feeding Similar Flat Items in Succession From a Stack Thereof, U. S. Pat. No. 5,501,444 to Yukimachi entitled Sheet Supply Apparatus, and U.S. Pat. No. 5,058,874 to Miyoshi entitled Automatic Document Conveying Device, each mention an automatic sheet feeder that has the pickup roller lifted away from the paper stack at regular intervals by a bell crank device. U.S. Pat. No. 4,212,456 to Ruenzi entitled Apparatus for Automatically Feeding Individual Sheets From a Stack Through an Office Machine, mentions an automatic sheet feeder used in conjunction with a page separator, U.S. Pat. No. 5,240,239 to Kim entitled Paper Sheet Feeding Apparatus, shows an automatic sheet feeder that sequentially loads sheets into a printer. Both U.S. Pat. No. 4,925,062 to Tsukamoto entitled Sheetfeeder and U.S. Pat. No. 4,884,796 to Daboub entitled Singulator for Document Feeder, use solenoids in their gearing mechanisms in conjunction with their automatic sheet feeders.
I have observed that when a printable medium is used in a sheet feeding device that has a greater thickness or different dimensions than that of standard paper, the sheet separator is not usable. This causes difficulty with the printing process and makes it necessary to manually feed the printable medium through the sheet feeder.